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Amine El Khalifi, 29, of Alexandria was arrested Friday and charged with attempting to use a weapon of mass destruction. He was ordered held pending indictment. Federal court documents say El Khalifi is a native of Morocco who has been living illegally in the United States for more than a decade.

El Khalifi stood quietly as his lawyer informed Judge John Anderson.

An FBI affidavit traces the evolution of El Khalifi's alleged plotting, saying he revealed his intentions to an undercover FBI operative he thought was a member of al-Qaida.

According to the affidavit, El Khalifi spoke in December of wanting to attack a synagogue and Army generals. But within days, he was settling on a new plan to bomb a bustling Washington restaurant at lunchtime, the affidavit states. In January, he changed his mind, saying he wanted to blow himself up inside the Capitol as an act of martyrdom and chose the date of Feb. 17, authorities said.

The man's arrest came Friday after a lengthy FBI investigation.

El Khalifi went as far as to don a suicide vest provided to him by the undercover operatives before he was arrested, according to an FBI affidavit. The suicide vest turned out to be inert, and a gun that had been provided to him to shoot his way past security guards also was inoperative. Officials say the public was never in danger.

According to court papers, El Khalifi told his supposed co-conspirators that he would be happy if he could kill 30 people in the attack.

It is not entirely clear how El Khalifi came to the attention of authorities. Court papers state only that a confidential source reported El Khalifi to the FBI in January 2011 after he allegedly met with others at an Arlington residence and told others that the group needed to be ready for war, and that he agreed with others who believed the war on terror to be a war on Muslims. One individual at that meeting produced what appeared to be an AK-47 rifle.

El Khalifi, who is being represented by the federal public defender, faces up to life in prison.

At the courthouse Wednesday, an acquaintance of El Khalifi who asked that his name not be used, said he knew El Khalifi from the Falls Church mosque they both attended and that he stood out because of the tattoos he had on his neck and arms and his mohawk haircut.

The acquaintance said El Khalifi normally attended noon prayer at the mosque but on the day he was arrested, he came early and appeared nervous and out of sorts.

Members of the Council on American Islamic Relations denounced El Khalifi's actions but also said the FBI is pressuring Muslims here in the U.S. to become informants, a practice they say is unnecessary and dangerous.